1. Field of the Invention
The present invention relates to a method and an apparatus for winding a cuff having an inflatable chamber into which pressurized gas is to be supplied, around a body portion of a living subject, in measuring blood pressure of the subject.
2. Related Art Statement
When blood pressure of a living body or subject is measured, a cuff having an inflatable chamber into which pressurized gas is to be supplied, is wound around a body portion of the subject, to press arteries running in the body portion. The manner of winding of the cuff around the body portion influences the relationship between the gas pressure in the inflatable chamber of the cuff (hereinafter, referred to as the "cuff pressure" or "pressing pressure") and the state of pressing of the arteries in the body portion. That is, even at the same cuff pressure or pressing pressure, the state of pressing of the arteries in the body portion may change depending upon the manner of winding of the cuff around the body portion. Hence, it is widely recommended that a cuff be wound around a body portion in such a manner that two or three fingers can easily be inserted between the cuff and the body portion.
Meanwhile, a body portion of a living subject, such as an upper arm or a femur, very easily deforms. Thus, the winding of a cuff around the body portion needs the skill of a user such as a doctor or a nurse. Moreover, the relationship between cuff pressure and state of pressing of arteries in a body portion may change among individual subjects. The change of relationship results in lowering the accuracy of blood pressure (BP) measurements of the individual subjects.
In the case where a pulse wave is detected as a pressure oscillation produced in an inflatable chamber of a cuff in synchronism with heartbeat of a subject, the change of relationship influences the waveform of the pulse wave detected. In this respect, too, it is desirable that the cuff be wound around the body portion in an appropriate manner.